wideband acting strange

[jbeaton9292]

ok lets start by saying i have a ngk afx wideband that i am running narrowband simulation in front o2 spot.

now for my question when im sitting at idle which i have set to 950 the car idles fine and is in closed loop but the wideband shows 16.0 afr which is the max on this specific wideband. not sure why it does this any idea?

next in my data log via ecmlink v3 full i show my car in closed loop and my fronto2 at .2v and stays there i begin driving and the o2 will cycle between .2 and .8 then anytime i stop for a light or traffic sign it goes back to not cycling at .2 this is messing with my combinedft setting and i just want to know why it is doing this im really confussed

 

[codym]

Bad sensor or you're running really lean.

 

[jbeaton9292]

Well ive found based on a log posted on ecmlink forums that it is most deffinatly trying to run lean my combinedft is up at 30% trying tell the ecu opposite of what it knows to do

How do i lower the combinedft im assuming i do this by adjusting the airflow sliders based on the maf hz at idle correct?

 

[codym]

I don't personally have link right now, but yes I believe you are correct. You want to adjust the slider to keep the total fuel trim around 100 on a 1g.

 

[Marchev]

I don't personally have link right now, but yes I believe you are correct. You want to adjust the slider to keep the total fuel trim around 100 on a 1g.

Combined FT should be as close to zero % as possible, not 100.
OP check out the tutorial videos on ecmtuning, they will show you what and how to adjust better than anyone can explain

 

[codym]

Combined FT should be as close to zero % as possible, not 100.
OP check out the tutorial videos on ecmtuning, they will show you what and how to adjust better than anyone can explain

I always thought it was 100% on a 1st Gen, maybe I'm getting mixed up..

While in closed loop the ECU works to maintain the 14.7:1 ratio your seeing by including and updating the fuel trim. Right now the feedback from the stock narrowband sensor is causing the ECU to remove as much fuel as it can to reach 14.7:1 and that's why the trim is 81.2. By telling the MAFT you have bigger injectors it will lower the airflow reported to the ECU so that the ECU thinks it need less fuel to reach the stoch. The O2 sensor will tell the ECU that it's now leaner than it was, the ECU will subtract less fuel than it was and the fuel trim will start to move back towards 100% all while still targeting the same closed loop 14.7:1 AFR.

If you go too large the trims will go past 100% and the ECU will start adding fuel to what it calculated is needed from the airflow counts.

The manual for the MAF-Translator says:

• Adjust the BASE knob to keep the total trim between 80% and 100% during steady state driving (35-45 mph). To lean out the fuel curve, set the AUX/BASE to a larger injector size. To richen the fuel curve, set the AUX/BASE to a smaller injector size.


"Total trim" is the 'product' of the active fuel trim and the O2 trim. At 120Hz , Midtrim*O2trim = Total Trim (low trim<88Hz airflow, 88<mid trim<180, 180<high trim).